The integration of photovoltaic structures in architecture with commercial modules has created numerous technical and optical problems which are dealt with, for example, in German patent documents DE 19 00 069, DE-GM 79 20 669, DE 34 19 299, DE GM 82 12 100 and DE 33 37 658. For fastening conventional photovoltaic modules, fastening elements passing through the roof covering and to the supporting roof construction must be mounted on fastening devices and must be individually designed for the particular roof covering system which is used. Standardization, which is difficult and hardly sensible in view of the relatively small numbers of pieces which had to be provided, was not practical. The fastening of commercial photovoltaic modules required a storm-resistant anticorrosion construction which was so attached that it would not loosen in the course of time and generate flapping noises in the wind.
Whenever a fastening device passed through a conventional roof covering, sealing problems were encountered. Indeed, the long-term tightness of a roof covering traversed by such fastening elements could not be guaranteed because of the daily thermal stresses and changes resulting from aging of the roof. The fastening techniques employed were costly, involved large labor costs and required specially trained personnel.
In addition, existing technology often provided aesthetically unacceptable photovoltaic modules which did not harmonize with the traditional roof covering. For example, the photovoltaic module was often of a blue or black coloration and in commercial systems was surrounded by a silver or colored frame, neither of which harmonized with the color scheme of conventional roof coverings. Because of these problems, mass production of photovoltaics to reduce costs of application of photovoltaic units to existing roof coverings did not materially progress in recent years.